Engine speed regulator apparatus and the like

ABSTRACT

This disclosure deals with a novel engine speed regulator apparatus in which, through the combined use of frequency-tovoltage converter and voltage detector networks, a control may be actuated at a predetermined frequency corresponding to the engine speed beyond which it is desired to regulate, to prevent the engine spark plugs from thereupon receiving further ignition energy. The techniques here-involved, moreover, are of broader applicability than this particular application to engine speed regulation.

United States Patent Minks Apr.9,1974

ENGINE SPEED REGULATOR APPARATUS AND THELIKE [76] Inventor: Floyd M. Minks, Rt. 1, Box 66,

Kissimmee, Fla. 32741 22 Filed: Sept. 17, 1971 21 Appl. No.: 181,402

[52] US. Cl. 123/102, 123/148 E, 307/88.5 [51] Int. Cl. F02p 9/00 [58] Field of Search 123/98, 102; 307/233, 252 J;

[56] References Cited UNITED STATES PATENTS 3,702,407 11/1972 Sharp 307/233 3,581,720 6/1971 Hemphill 123/102 3,582,679 6/1971 Carp 307/233 3,176,161 3/1965 Vertrees... 307/252 .1 3,242,346 3/1966 Skoubo 322/32 X OTHER PUBLICATIONS Pulse, Digital, and Switching Waveforms by Millman & Faub, McGrawHill Book Co., copy in Millers office.

Primary ExaminerLaurence M. Goodridge Attorney, Agent, or FirmRines & Rines; Shapiro and Shapiro [57] ABSTRACT This disclosure deals with a novel engine speed regulator apparatus in which, through the combined use of frequency-to-voltage converter and voltage detector networks, a control may be actuated at a predetermined frequency corresponding to the engine speed beyond which it is desired to regulate, to prevent the engine spark plugs from thereupon receiving further ignition energy. The techniques here-involved, moreover, are of broader applicability than this particular application to engine speed regulation.

7 Claims, 1 Drawing Figure /3 VOLTAGE IGNITION g gs -n SUPPLY SYSTEM PLUGS SCR ? I D1 To R3 PAIENIEBAPR 9 I974 1802.400

VOLTAGE IGNITION g gg y; SUPPLY SYSTEM PLUGS l I I I SCR INVENTOR FLOYD M. MINKS WWW ATTORNEYS ENGINE SPEED REGULATOR THE LIKE The present invention relates to engine speed regulator apparatus and the like, being more particularly concerned with regulating the speed of automotive engines and similar systems, but being more broadly adapted to enable generally the indication of the attaining of predetermined speeds or frequencies.

Prior proposals for regulating engine speed have involved the interruption of the power supplied to one of the control elements within the ignition system. This interruption has been accomplished by generating a voltage which is a function of engine speed, the voltage being zero at zero engine speed, and comparing the value of this voltage with voltage-sensitive thresholdlevel elements, such asa zener diode or the like. While being used in practice, such systems'are nonetheless subject to several disadvantages, including sensitivity to temperature. Such' elements as zener diodes, moreover, are generally less reliable than linear elements, such as resistors and capacitors, and the nature of this type of circuit usually requires that the ignition system must be tailored at the time of the manufacture to permit its inclusion, inherently preventing addition at a later date and requiring manufacture of entire special ignition APPARATUS AND systems. Such circuits, furthermore, generally require.

an input voltage in which not only the frequency, but

V the amplitude, is also accurately known. An illustration of this type of circuit is presented, for example, in my prior United States Letters Patent No. 3,334,719, issued Oct. 20, 1970, for Speed Limiting Ignition System.

An objective of the present invention, accordingly, is to provide a new and improved engine speed regulator apparatus that shall not be subject to the abovedescribed disadvantages, but that, to the contrary, eliminates the necessity for clippers and voltage-level devices, such as zener diodes and the like and, instead, enables the use of simple network circuits embodying reliable components particularly adapted for use with ignition systems and devoid of thetemperaturesensitivity and other requirements of zener diode and similar circuits. Y

A further object of the invention is to provide a novel frequency indicating apparatus of more general utility, as well. i

Other and further objects will be explained hereinafter and are more particularly pointed out in the appended claims. v

In summary, in its application to engine speed control, the invention 'embodiesengine speed regulator apparatus having, in combination, means for supplying power to engine spark plug means; normally ineffective control means connected, when rendered effective, to prevent the supplying means from supplying power to the spark plug means, thereby to reduce engine speed;

' a source of alternating-current voltage the frequency of which is related to engine speed; frequency-to-voltage converter means connected between the source and said control means to produce an output voltage substantially proportional to the source voltage and the frequency thereof; voltage detector means connected between the source and said control means to produce an opposite polarity output voltage substantially propo'rtioned to the source voltage; means for combining said opposite polarity output voltages such that, when substantially equal, the control means is rendered ef- 3,802,4 OO I fective; and means for presetting the frequency at which said output voltages become substantially equal.

The invention will now be described with reference to the accompanying drawing, the single FIGURE of which is a combined block and schematic circuit diagram illustrating a preferred embodiment shown, for purposes of illustration, as applied to engine speed control applications.

Referring to the drawing, engine spark plugs, so labeled, are schematically shown receiving the ignition energy periodically from a voltage supply 1 under the control of an ignition system 3, such as described, for example, in my prior United States Letters Patent No. 3,395,686, issued Aug. 6, 1968, for Blocking Oscillator Circuit and Capacitor Discharge Ignition System Employing the Blocking Oscillator Circuit. Other suitable ignition systems may similarly be employed, such not forming any part per se of the novelty of the present invention.

A source of pulsating or alternating current is generically designated at Al, the frequency of which is a function of the engine speed. The source Al may either be an alternator driven'by the engine or, indeed, a source of alternating-current waveform available at some location within the ignition system, particularly if the ignition system contains a converter that is triggered once per cycle. In any event, the altematingcurrent voltage emanating'from the source A1 is shown applied in parallel connection to two networks I and II.

The network I isa frequency-to-voltage converter network embodying a series capacitor C, a shunt rectifier D1, a series diode rectifier D2 and an output shunt capacitor C. Networks of this kind are known in the art and are often used in such devices as tachometers. The property of these networks is that the capacitor C will become charged through the diode D1 on one-half cycle of the alternating source of Al and will then be forced to discharge through the series diode D2 to store energy in the capacitor C. In the normal operation of this network I, the voltage on the output capacitor is at all times small compared to the input voltage, such that the voltage across the capacitor C essentially changes the entire rangeof the voltage from the source A1. From the basic inter-action between such a capacitor and its current and voltage change, the average value of the current delivered to C after rectification by diodes D1 and D2, can be computed. This current is generally proportional to both the peak-to-peak amplitude of the voltage of Al and the frequency of the same.

The second network II, connected in parallel with network I, embodies a resistor R1 and a diode rectifier D3 poled oppositely to that of the series rectifier D2 of network I. This network II will act as a detector for the voltage of the source A1, producing a current contribution across capacitor C that is substantially proportional to the voltage from the source Al, but of opposite polarity to that resulting from the action of the series rectifier D2 of the network I. There thus results across the capacitor C, a combination of the oppositepolarity outputs of the networks I and II. For some particular frequency, these outputs will be substantially equal, producing an overall output that is substantially zero. Below such particular frequency, the output is negative, and above, it is positive.

In accordance with the present invention, the combined output of the networks I and II is applied through a buffer transistor amplifier T to a control or signaling device, such as an SCR electronic switch, so-labelled. Specifically, the upper output terminal of the networks I and II is connected to the base electrode of buffer T, the output of which is applied from the emitter through R2 to the gate electrode of SCR, with the further emitter resistor R3 decoupled by C2, and with the cathode of SCR being connected to the ground terminal G. The control or signaling switch element SCR has its anode connected either to the output of the voltage supply 1 or to an appropriate terminal within the ignition system 3, such that when SCR is rendered effective or conductive, voltage is prevented from being supplied to the spark plugs, and the engine speed appropriately starts to run down. As before stated, this occurs at that predetermined frequency at which zero resultant output voltage is produced from the networks I and II (neglecting, of course, the small input voltage required for bias .on the control elements of SCR and the buffer amplifier T). By appropriate adjustment of the value of the network capacitors and the resistor R1, one may preselect this predetermined frequency corresponding to the speed beyond which it is desired that the engine be regulated and at which the output from the network I, proportional to the product of voltage and frequency of Al, substantially equals the opposite polarity output developed by network II and proportional to the voltage of Al. Though there are several elements involved in these networks, this frequency is determined almost entirely by resistor R1 and capacitor C, with very minor contributions by the othercomponents.

While the invention has been described in terms of having the control device SCR actually prevent the supplying of spark voltage to the spark plugs, it is to be understood that, in some instances, it may be desired merely to indicate that the engine speed has reached a predetermined value. Under such circumstances, the conduction of the switching SCR may be used as an electrical signal, or applied to an indicator lamp or the like for such purposes; or, indeed, the bufier amplifier T and the SCR may be replaced by a conventional indicating meter movement connected across C' and producing a very expanded-scale tachometer. This would, of course, be usable only when the rpm varied only over a small range. ln such an event, the meter may be considered as normally ineffective until the desired frequency has been reached, at which point the desired indication will be produced. Small deviations from this exact preset frequency will also be readable, as well.

With the use of a solid-state switch SCR, furthermore, it is desired that the shutting off of the energy to the spark plugs be distinct, abrupt and controlled, and also that the engine not be allowed to slow down too much before the switching SCR is again rendered ineffective or open-circuited. The buffer stage T assists in this function by preventing current being drawn from the gate of the conductive SCR from charging C.

Typical circuit values that have been found to work admirably in practice with, for example, snowmobile engine systems, have involved a network series capacitance C of 2200 microfarads, type IN 661 diodes D1 and D2, a capacitor C of about microfarads, a resistor R1 which may be variable to adjust the desired frequency of up to about 39 Kohms, and a network diode D3 of the IN 647 type. In this system, the emitter resistors R2 and R3 connected with the transistor T and the gate of SCR, may have values of about 680 and 560 ohms, respectively, and the bypass capacitor C2 may have a value of 0.01 microfarads. In tests with such sysv terns, over the normal temperature and operating ranges of the snowmobile engines, controlled shut-off of ignition and consequent reduction in engine speed was obtained at the preset speed, within better than one percent of error.

Further modifications will occur to those skilled in the art and all such are considered to fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. Engine speed regulator apparatus having, in combination, means for supplying power to engine spark plug means; normally ineffective control means connected, when rendered effective, to prevent the supply means from supplying power to the spark plug means, thereby to reduce engine speed; a source of alternating current voltage the frequency of which is related to engine speed; frequency-to-voltage converter means connected to said source and including energy storage means and means for delivering a current to said storage means the average value of which is substantially proportional to the peak-to-peak amplitude of said source voltage and the frequency thereof, thereby to apply a first output voltage to said storage means; voltage detector means connected to said source and said energy storage means for producing a second output voltage substantially proportional to the source voltage and for applying said second output voltage to said storage means with polarity opposite to that of said first output voltage, whereby the average voltage upon said storage means varies in accordance with the extent to which one of said output voltages counteracts the other; means connecting said storage means to said control means for rendering said control means effective when said output voltages are substantially equal; and means for presetting the frequency at which said output voltages become substantially equal.

2. Engine speed regulator apparatus as claimed in claim 1 and in which said source comprises an alternator, the said frequency-to-voltage converter means comprises a network the output current of which is substantially proportional to the alternator voltage.

3. Engine speed regulator apparatus as claimed in claim 1 and in which said frequency-to-voltage converter means and said voltage detector means both comprise networks connected in parallel with one another.

4. Engine speed regulator apparatus as claimed in claim 3 and in which the frequency-to-voltage converter network comprises series and shunt diodes and capacitances and the voltage detector network comprises a series diode poled oppositely to the frequencyto-voltage converter network series diode.

5. Engine speed regulator apparatus as claimed in claim 1 and in which said control means comprises a threshold voltage-operated electronic switch.

6. Engine speed regulator apparatus as claimed in claim 5 and in which buffer transistor means is disposed between said electronic switch and said networks.

7. Engine speed regulator apparatus as claimed in claim 3 and in which the said presetting means comprises means adjusting resistance and capacitance values of said networks. 

1. Engine speed regulator apparatus having, in combination, means for supplying power to engine spark plug means; normally ineffective control means connected, when rendered effective, to prevent the supply means from supplying power to the spark plug means, thereby to reduce engine speed; a source of alternating current voltage the frequency of which is related to engine speed; frequency-to-voltage converter means connected to said source and including energy storage means and means for delivering a current to said storage means the average value of which is substantially proportional to the peak-to-peak amplitude of said source voltage and the frequency thereof, thereby to apply a first output voltage to said storage means; voltage detector means connected to said source and said energy storage means for producing a second output voltage substantially proportional to the source voltage and for applying said second output voltage to said storage means with polarity opposite to that of said first output voltage, whereby the average voltage upon said storage means varies in accordance with the extent to which one of said output voltages counteracts the other; means connecting said storage means to said control means for rendering said control means effective when said output voltages are substantially equal; and means for presetting the frequency at which said output voltages become substantially equal.
 2. Engine speed regulator apparatus as claimed in claim 1 and in which said source comprises an alternator, the said frequency-to-voltage converter means comprises a network the output current of which is substantially proportional to the alternator voltage.
 3. Engine speed regulator apparatus as claimed in claim 1 and in which said frequency-to-voltage converter means and said voltage detector means both comprise networks connected in parallel with one another.
 4. Engine speed regulator apparatus as claimed in claim 3 and in which the frequency-to-voltage converter network comprises series and shunt diodes and capacitances and the voltage detector network comprises a series diode poled oppositely to the frequency-to-voltage converter network series diode.
 5. Engine speed regulator apparatus as claimed in claim 1 and in which said control means comprises a threshold voltage-operated electronic switch.
 6. Engine speed regulator apparatus as claimed in claim 5 and in which buffer transistor means is disposed between said electronic switch and the said networks.
 7. Engine speed regulator apparatus as claimed in claim 3 and in which the said presetting means comprises means adjusting resistance and capacitance values of said networks. 